A communication method applied to a computer system that includes a first subsystem and a second subsystem. A safety level of the first subsystem is higher than a safety level of the second subsystem. The first subsystem includes a memory access checker. The method includes the memory access checker receives a memory access request from a memory access initiator, determines, based on preconfigured memory safety level division information, whether a safety level of a memory to be accessed by the memory access initiator matches a safety level of the memory access initiator, and allows the memory access initiator to access the memory address when the safety level of the memory matches the safety level of the memory access initiator.